1. Field of the Invention
This invention is related to the structure and design of a concealable chip leadframe unit, it is more specifically related to the structure and design of a chip leadframe unit which is capable of been placed underneath the chip and been reduced in the leadframe volume.
2. Description of the Related Art
One of the major concern in the printed circuit board layout is how to fully use the limited area in a printed circuit board, especially when the information and electronic products nowadays move toward the trend of multi-function design, how to install more functional transistors possible in the limited printed circuit board space is the major technical bottleneck to be overcome; in addition, the electronic products nowadays, especially personal portable products such as: personal digital assistant (PDA), Note Book, multi-function portable disc, tablet PC, system or cellular phone, etc., have focused on providing portable convenience for the users and thus headed toward smaller volume and compact design, therefore, in addition to reduce the printed circuit board size, the improvement on the structure and design of other electronic components is also indispensable.
As shown in FIGS. 9 and 10, it is a prior art semiconductor packaging structure wherein leadframe 30 is installed underneath chip 20 in the conventional semiconductor package 10, an encapsulated body 40 is used to enclose and seal the whole structure, leadframe 30 is used as a media to connect chip 20 to the printed circuit board, the leadframe 30 comprising of multiple rows of leads 301 protruding along the lower two sides of semiconductor package 10, not only the volume of leadframe 30 in this structure is difficult to be reduced, but also the electrical resistance stays high, therefore, with this structure, it is difficult to meet the trend of compact and high speed printed circuit board and electronic components.